Process for obtaining transparent effects on regenerated cellulose fibers



Patented May 2, 1950 PROCESS FOR OBTAINING TRANSPARENT EFFECTS ON REGENERATED CELLULOSE FIBERS Paul Walter Steinlin, Herisau, Switzerland, as-

signcr to Airtiengescllschaft Cilander, Herisau, Switzerland, a corporation of Switzerland No Drawing. Application July 18, 1947, Serial No. 761336. in Switzerla-ndApril22, 1943 7 Claims. 1

This invention relates to a new and improved process for obtaining transparent effects on textile materials and has particular relation to a process of this type, adapted to be used in the treatment of textile fabrics consisting. at least partly of cell-wool made of regenerated cellulose.

The main object of the present invention is to provide a process for manufacturing textile materials which consist at least partly of cell-wool mad of regenerated cellulose, and are distinguished by transparent appearance as well as softnessv Another object of this invention is to provide a process in which the starting material of the above mentioned type is subjected to a combined treatment with acid and alkali under conditions which result in transparent effects on said material without adverse efiects, such as stilfness and brittleness.

It is also an object of the present invention to convert textile materials consisting at least part- 1y of cell-wool: made of regenerated cellulose, into transparent fabrics of high. lustre, softness and durability.

Otherobjects and the advantages of the invention willbe apparent from the following specification which describes, by way of example, some preferred embodiments of the invention.

Transparent fabrics, also known as organdies, have, as av rule, been made from cotton materials, particularly muslin, or to a lesser extent, from voile or other fine fabrics, such as cambric. Organdies of especially fine quality were made from natural silk.

Prior to my'present invention, various attempts havebeen made to obtain transparent effects on textile fabrics consisting partly or completely of cell-wool made of regenerated cellulose by applying, to cell-wool materials the known methods used in the treatment of cotton fabrics. However, these attempts proved inadequate, as, in spite of the various attempts to adapt the working conditions and the composition of the treating agents to the nature. of cell-wool containing materials, it was not hitherto possibleto produce marketable transparent fabrics from cell-wool materials. made of regenerated cellulose. Transparent fabrics produced according to the processes hitherto known from cell-wool material made of regenerated cellulose are horny, brittle and stifiened and not suited for practical use;

I have now found that transparent fabrics which satisfy all requirements of appearance, lustre, softness and durability, and show a high degree of transparency combined with a remarkable clearness of weave, can be produced from cell-wool containing materials made of regenerated cellulose by treating such materials in the manner and under the conditions described hereinaiter.

According tothe present invention, the textile material containing cell-wool made of regenerated cellulose is first treated with cold, strong sulfuric acid and subsequently with hot, strong caustic alkali, under predetermined conditions of the concentration of the acid and alkali solutions, and temperature and duration of the respective treatments.

In carrying out the present process, fabric containing the cell-wool made of regenerated cellulose is first treated with a relatively concentrated sulfuric acid at a low temperature for a few seconds and, after removal of the acid, with a concentrated hot solution of caustic alkali also for a few seconds only. The concentration of sulfuric acid in this treatment amounts to about 45- O Be. and the treatment with sulfuric acid takes place substantially at 0-15 C. for 8-10 seconcls. The caustic alkali solution has a concentration of about 30 to 36 Be, and the alkali treatment is carried out substantially at 50 C. during 8-10 seconds.

I have found that by the application of these steps, transparent appearance and also softness are imparted to fabrics containing cell-wool made of regenerated cellulose if all the above mentioned conditions of concentration, temperature and time are observed, while the desired result is not obtained if said conditions are not correctly applied,

The process of the invention may be applied to fabrics which consist only or fibres made of regenerated cellulose, or to fabrics containing such regenerated cellulose woven with cotton and also to fabrics woven with mixed yarn of cotton and such regenerated cellulose. Fabrics in which these spun structures are present in various combinations either in plain or pattern weave, including, of courses, embroidery or Swiss; dotted weave, may'also be treated accordingtc the pres ent process; It is to be understood that in the present specification and claims the term cellwool" fabric consisting at least partly of cellwool made of regenerated cellulose is used to lncludeall of the" here mentioned types of fabrics consisting of or containing such cell-Wool or regenerated cellulose.

I prefer to treat the fabrics after they have been freed from size: and are bleached. However, raw fabrics may also be treated according to-the present process, which may be applied to them in any phase of their pretreatment.

In processing a fabric according to the present invention, the acid-alkali treatment may be repeated in order to obtain an increased effect, and it is, of course, necessary to remove the acid or alkali from the fabric prior to a subsequent treatment with alkali or acid, respectively.

Example 1 A fabric consisting only of cell-wool made of regenerated cellulose is singed, bleached, tentered, and dried, and is then treated for 8 seconds with sulfuric acid by passing it in stretched condition and under rolling friction through a sulfuric acid bath of 45 B. at 15 C. The fabric is now rinsed with water and neutralized, and is then treated for 8 seconds with sodium hydroxide by passing it through a sodium'hydroxide solution of 30 B. at 50 C. Thereafter the material is well cooled, neutralized, and, if desired, dyed, bleached again and blued and tentered as usual. The result is a fine transparent effect.

Example 2 A fabric consisting only of cell-wool made of V regenerated cellulose, which has been pretreated as in Example 1 by singeing, bleaching, tentering, and drying, is treated with sulfuric acid of 46 B. at C. for 8 seconds. The acid is removed from the fabric by rinsing and neutralizing, and is then treated under tension with an aqueous sodium hydroxide solution of 36 B. at 50 C. for 8 seconds. After rinsing, neutralizing and tentering, the fabric is treated with sulfuric acid of 47 B. at 0 C. for 8 seconds, and after removing the acid by rinsing and neutralizing, it is treated with sodium hydroxide solution of 30 B. at 50 C. for 8 seconds. The fabric is then rinsed and neutralized and subjected to the finishing treatment described in Example 1.

Example 3 A fabric consisting of mixed cotton-regenerated cellulose cell-wool fibre yarn is singed, bleached and tentered and is then treated with sulfuric acid of 47 B. at 15 C. for 8 seconds. After the acid is removed by rinsing, the material is treated with a hot aqueous sodium hydroxide bath of 30 B. at 50 C. for 8 seconds under tension and roller pressure. It is then rinsed, neutralized and tentered and treated with sulfuric acid of 50 B. at 15 C. for seconds. The fabric is then rinsed and neutralized, and subjected to the action of an aqueous sodium hydroxide solution of 30 B. at 50 C. for 10 seconds.

Example 4 A mixed cotton-regenerated cellulose-cell-wool fabric is singed, bleached and tentered, and is then printed with a printing paste containing nitrocellulose and a softening agent, such as camphor, in mixture with titanium dioxide. The printed fabric is treated with sulfuric acid of 47 B. at C. for 8 seconds and rinsed with water to remove the acid. The rinsed fabric is treated with a hot aqueous sodium hydroxide solution of B. at 50 C. for 8 seconds under tension and roller pressure. It is then rinsed, neutralized and tentered, and treated with sulfuric acid of 50 B. at 15 C. for 10 seconds. After rinsing and neutralizing, the fabric is treated with an aqueous sodium hydroxide solution of 30 B. at 50 C. for 10 seconds. The treatment results in a patterned fabric showing opaque, non-transparent, white designs on a transparent background. If desired,

the fabric, treated according to this example, may be dyed either prior to or after the acid and alkali treatments.

Example 5 A mixed cotton-regenerated cellulose-cell-wool fabric is singed, bleached and tentered, and subsequently printed with a reserve consisting of gum. The printed fabric is treated in stretched condition and under rolling friction with sulfuric acid of 45 B. at 15 C. for 8 seconds, rinsed with water and neutralized. After neutralization, the reserve is substantially completely removed by washing, and a treatment with hot aqueous sodium hydroxide of 30 B. without tension at 50 C. for 8 seconds follows. This results in a crepe effect caused by contraction of the non-transparent portions of the fabric. Depending on the distribution of the reserve over the surface of the fabric, a so-called crepe-organdy is obtained if the unshrunk portions are preponderant. If, however, the shrunk portions are preponderant and there are only a few small patterned transparent areas, the result is a so-called opal-transparent product.

As shown by the above examples, patterned as well as plain transparent fabrics may be obtained according to the present process. The essential and indispensable steps of the process consist in the acid and alkali treatment or treatments under the above described conditions, and these steps may be combined with other steps known by themselves in order to obtain patterned or other effects. For example, the fabric may be printed with pigments in order to obtain opaque, non-transparent portions forming the desired pattern. The pigment carriers used in this modiflcation, for example, gums or artificial resins, may be resistant to acid and alkaline swelling agents and result in local non-transparent effects. Or, if desired, non-acidproof thickening agents may be used, which result in stiffened transparent designs in which the contrasting effect is due to'the pigmentation only. Furthermore, by printing in colors or by the use of colored reserves, many-colored effects may be obtained.

The fabrics may be dyed either before or after the treatment according to the present process, whereby, depending on the conditions of the treatment, various effects may be obtained, such as plain transparent effect, or, due to the different afiinity of the fibers for the dye in various portions of the fabric, shaded effects.

It is to be understood that in the present specification and claims the term cell-wool made of regenerated cellulose or regenerated cellulose cell-wool is used to denote textile materials, such as fibres, yarns or fabrics made of regenerated cellulose, either in the form of staple fibers or in other forms made of regenerated cellulose, and textile products obtained from such textile materials.

It is also to be understood that the present invention is not limited to the specific details described in the above examples and may be carried out with various modifications without departing from the scope of the invention as defined in the appended claims.

Reference is made to my co-pending application Serial No. 533,788, filed May 2, 1944, now abandoned, of which this a continuation-in-part.

What is claimed is:

1. A process for obtaining soft transparent effects on a fabric consisting predominantly of mall-wool made of regenerated cellulose, said process comprising a first step of treating said fabric with sulfuric acid of about 45-50 B. substantially at -15 C. for substantially 8-10 seconds, and a, second step of treating the fabric with an aqueous caustic soda solution of about 30-36 B. substantially at 50 C. for substantially 8-10 seconds.

2. A process for obtaining soft transparent effects on a fabric consisting predominantly of cell-wool made of regenerated cellulose, said process comprising a first step of treating said fabric with sulfuric acid of about 45-50 B. substantially at 0-l5 C. for substantially 8-10 seconds, and removing the acid from the fabric, a second step of treating the fabric with an aqueous caustic soda solution of about 30-36 B. substantially at 50 C. for substantially 8-10 seconds, removing the caustic soda from the fabric and subjecting it again to said first step, to the removal of acid, and to said second step.

3. A process for obtaining soft transparent effects on a fabric consisting predominantly of cell-wool made of regenerated cellulose, said process comprising a first step of treating said fabric in stretched condition and under rolling friction with sulfuric acid of about 4550 B. substantially at 0-15 C. for substantially 8-10 seconds, and removing the acid from the fabric, and a second step of treating the fabric with an aqueous caustic soda solution of about 30-36 B. substantially at 50 C. for substantially 8-10 seconds.

4. A process for obtaining soft transparent effects on a fabric consisting predominantly of cell-wool made of regenerated cellulose, said process comprising a first step of treating said fabric with sulfuric acid of about 45-50 B. substantially at 0-15 C. for substantially 8-10 seconds, and removing the acid from the fabric, and a second step of treating the fabric under tension with an aqueous caustic soda solution of about 30-36 B. substantially at 50 C. for substan tially 8-10 seconds.

5. A process for obtaining soft transparent effects on a fabric consisting predominantly of cell-wool made of regenerated cellulose and printed according to a predetermined pattern with a printing paste, said process comprising a first step of treating said fabric with sulfuric acid of about -50 B. substantially at 0-15 C. for substantially 8-10 seconds, and removing the acid from the fabric, and a second step of treating the fabric with an aqueous caustic soda solution of about 30-36 B. substantially at C. for substantially 8-10 seconds.

6. A process for obtaining soft transparent effects on a fabric consisting predominantly of cell-wool made of regenerated cellulose and printed according to a predetermined pattern with a, reserve, said process comprising a first step of treating said fabric with sulfuric acid of about 45-50 B. substantially at 0-15 C. for substantially 8-10 seconds, and removing the acid from the fabric, and a second step of treating the fabric with an aqueous caustic soda solution of about 30-30 B. substantially at 50 C. for substantially 8-10 seconds.

'7. A process for obtaining soft transparent effects on a fabric consisting predominantly of cell-wool made of regenerated cellulose, said process comprising a first step of treating said fabric with sulfuric acid of about 45-50 B. substantially at 0-15 C. for substantially 8-10 seconds, and removing the acid from the fabric, and a second step of treating the fabric with an aqueous caustic soda solution of about 30-36 B. substantially at 50 C. for substantially 8-10 seconds, cooling the fabric and removing the caustic soda therefrom.

PAUL WALTER STEINLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,288,885 Heberlein Dec. 24, 1918 1,998,577 Heberlein Apr. 23, 1935 2,085,946 Bodmer et a1 July 6, 1937 2,150,825 Ford et al Mar. 14, 1939 2,203,375 Weiss June 4, 1940 2,233,609 Heberlein et a1 Mar. 4, 1941 2,239,914 Heberlein Apr. 29, 1941 

1. A PROCESS FOR OBTAINING SOFT TRANSPARENT EFFECTS ON A FABRIC CONSISTING PREDOMINANTLY OF CELL-WOOL MADE OF REGENERATED CELLULOSE, SAID PROCESS COMPRISING A FIRST STEP OF TREATING SAID FABRIC WITH SULFURIC ACID OF ABOUT 45*50* BE. SUBSTANTIALLY AT 0*-15*C. FOR SUBSTANTIALLY 8-10 SECONDS, AND A SECOND STEP OF TREATING THE FABRIC WITH AN AQUEOUS CAUSTIC SODA SOLUTION OF ABOUT 30*-36* BE. SUBSTANTIALLY AT 50*C. FOR SUBSTANTIALLY 8-10 SECONDS. 